2021 Volume 107 Issue 6 Pages 412-421
Kakogawa Works of Kobe Steel, Ltd. has a set of sinter and pellet plants for the production of blast furnace raw materials. Recently, the use of magnetite fine ore has attracted attention while deterioration of iron ore grade. We clarified the problem of granulation and firing in using large quantity of magnetite fine ore, and developed countermeasures.
The most serious problem is forming un-granulated fine and huge agglomerates which causes decrease of permeability and deterioration of productivity. Since the strength of huge agglomerates is low, they collapse during transportation and sintering process. And then, they decrease permeability of packed bed and reduce productivity.
Selective granulation of magnetite fine ore is effective to suppress un-granulated fine and huge agglomerate. We propose the parallel granulating process which produce the double layer mini-pellet of magnetite fine ore which consists of core and adhesive layer. Double layered structure prevents collapse effectively because of aggregate effect of core particle. In addition, as the adhering layer of magnetite fine ore become thinner, magnetite is fully oxidized. Using double layer mini-pellet improves productivity and reduces coke consumption.